Punching device

ABSTRACT

This punching device includes a base unit and a reciprocating header unit mounted above the base unit. Guide pins maintain the two units in register and eccentric cams, journal-mounted to the header unit and bearing on the base unit, provide the reciprocating mechanism. The header unit carries a key bank and selected, individual keys may be depressed to lock associated punch elements in position below the header unit. When the header unit is lowered, the locked punch elements perforate a stack of test papers carried by the base unit, and provide punch holes at specific locations on each test paper corresponding to correct answers in a multiple choice quiz. The header unit includes a cam actuated release mechanism which releases all of the locked key punch elements simultaneously.

United StatesPatent Lee et al.

[15 3,656,686 1451 Apr. 18, 1972 [54] PUNCHING DEVICE [72] Inventors: James R. Lee, 249 West Jewel, Kirkwood,

Mo. 63122; James V. De Lurgio, l924 Berra Court, St. Louis, M0 631 10 22 Filed: Mar. 3, 1970 [21] Appl.No.: 16,158

52 05.0 ..234/1,234/ll1,234/ll6 151 mu. ..G06k 1/08 581 FieldoiSearch ..234/1,91-93,111,

I [56] References Cited UNITED STATES PATENTS 1,945,794 2/1934 Werk,Jr. '.....234/92 1,680,054 8/1928 Lebeis Primary Examiner-James M. Meister Artomey-Cohn and Powell [57] ABSTRACT- This punching device includes a base unit and a reciprocating header unit mounted above the base unit. Guide pins maintain the two units in register and eccentric cams, joumal-mounted to the header unit and bearing on the base unit, provide the reciprocating mechanism. The header unit carries a key bank 'and selected, individual keys may be depressed to lock associated'punch elements in position below the header unit. When the header unit is lowered, the locked punch elements perforate a stack of test papers carried by the base unit, and provide punch holes at specific locations on each test paper corresponding to correct answers-in a multiple choice quiz.

The header unit includes a cam actuated release mechanism which releases all of the locked key punch elements simultaneously.

21 Claims, 15 Drawing Figures mmmmwmz Y I 3,656,686

SHEET REF 5 65 Jib/@Z'LAZ' J4M5 H 0,54 0 66 /0 PATENTEDAPR 18 I972 SHEET 5 6F 5 0 oo o 00 oo 09090000 00990900 lw00900009 09009000 90000990 00000090 @700009000 90000009 00009900 000000090 09090090 000900900 90000000 909099000 [ill 00900009 090000009 PUNCIIING DEVICE BACKGROUND OF THE INVENTION This invention relates in general to a punching device and in particular to a punching device for use in the grading of multiple choice test papers. Multiple choice tests are in widespread use in schools, colleges and industry throughout the United States and provide a convenient means of assessing a students knowledge on a variety of subjects. In general, several choices of answer are presented to the student which are responsive to a specific question and the student is required to indicate his choice by marking one of several blocks, each corresponding to a possible choice of answer. The grader of the papers then compares the students answers to the correct answers in order to assess the performance of the student in the test.

One way in which this comparison has been made in the past is by hand punching a stack of test papers to correspond with a master test answer paper. There is no known way of achieving this result by means of an automatic, multiple punching machine. Such punching devices as exist for punching paper sheets or other material are generally unsuitable for the task of grading test papers.

Multiple punch machines are known in the prior art but, in general, they do not permit the depressing and locking of a selected number of key punches within a two-dimensional key bank. Existing punches are invariably limited to conditioning selected punches along a single line of such punches by means of sliding limit pieces, or similar devices. Further, the punch pressure of this type of punch is usually applied by means of a hinged lever which would not apply even pressure to keys distributed in a two-dimensional key bank.

SUMMARY OF THE INVENTION This punching device may be used for grading multiple choice test papers and it is adapted for use with a two-dimensional key bank. Selected, depressed keys may be locked into a hard, punching condition and released automatically and simultaneously. Punching pressure is evenly applied by a reciprocating header unit. i

The device includes a base unit, and a header unit mounted in guided, reciprocating relation above the base unit. The reciprocating means includes an offset cam means interconnecting the base and header units and the header unit is guided, relative to the base unit, by means of a plurality of pins attached to one of the reciprocating units and slidably received by the other of the reciprocating units.

The header unit carries a plurality of punching units, each of said units including a depressible key plunger element, mounted in latchable relation to the header unit, and a punch element aligned with an associated key plunger element. Each punch element is engageable by an associated plunger element in the latched position of the plunger element whereby said latched plunger element locks the punch element into a hard, punch condition. Release means is provided which selectively unlatches the depressed plunger elements.

The reciprocating motion between the base and header units is provided by a pair of shafts, mounted to the header unit in side-by-sicle relation and carrying the offset cam means. Each shaft includes opposed pinions, and the pinions at associated ends of each shaft are interconnected in coupling relation by a movable rack.

The base unit includes side support members and the offset cam means includes ball race elements secured to each end of each shaft and received by an associated side support member in joumaled relation.

The header unit includes a housing having spaced upper and lower support plates, each of said plates including a plurality of associated apertures in register, associated apertures receiving a key plunger element in sliding relation. Each plunger unit includes spring means interconnecting each key plunger element to the header unit. The spring means has both torsion and compression capability and is adapted to rotate a depressed plunger element to a latched position and, on unlatching, to return the plunger element to a non-depressed position.

The header unit includes a retention plate carrying the punch elements in freely depending relation, each punch element including a head, engaging the retention plate whereby said plate lifts the punch elements when the header is raised.

The release means includes a release plate carried by the header unit in transversely movable relation, the release plate being provided with a plurality of slots receiving the plunger elements. Each plunger element includes a projecting latch element and the apertures of the lower support plate engagingly retain the projecting latch element in the nondepressed condition. The lower support plate includes an abutment face engaging said latch element in the depressed condition.

The release plate is disposed subjacent of the lower support plate and includes shoulder means adjacent each latch element in the latched position. Translational movement of the release plate engages the shoulder means with the latch elements of depressed plunger elements and rotates said latch elements into engageable alignment with associated lower support plate apertures whereby said plunger elements are automatically retracted into said apertures. The release plate is actuated by a release cam means carried by the header unit.

The base unit includes a removable carrier plate adapted to carry the paper sheets to be punched. Said carrier plate includes a plurality of apertures operatively aligned with associated apertures in the housing support plates and adapted to receive a punch element, whereby to punch the paper sheets. A plurality of pins attached to the header and depending therefrom are receivable incompatible apertures in the carrier plate and serve to align said carrier plate with said header unit. An alignment plate supports the punch element ends.

The invention provides a method of grading test papers by the following steps: aligning a plurality of key plunger elements in a key bank above a plurality. of associated punch ele ments; torsionally spring-loading the key plunger elements; depressing and thereby rotating selected key plunger elements, corresponding to correct test answers, to a compressibly spring-loaded, latch position, to lock associated punch elements into a hard, punching condition; aligning a stack of test papers below the punch elements; reciprocating the key bank; and finally rotating the selected key plunger elements out of the latched position to torsionally spring-reload the depressed plunger elements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view of the punching device, cross sectional in part;

FIG. 2 is a side elevational view taken on line 2--2 of FIG.

FIG. 3 is a fragmentary, cross sectional view taken on line 33 of FIG. 1;

FIG. 4 is a perspective view of the header unit cover plate;

FIG. 5 is a perspective view of the header unit gear housing and wear plate;

FIG. 6 is a perspective view of the header unit release plate;

FIG. 7 is a perspective view of the header unit punch retention housing;

FIG. 8 is a fragmentary cross sectional view illustrating the relationship of key punch parts with one key depressed and the header unit in the raised position;

FIG. 9 is a similar view to FIG. 8 but with the header unit i the lowered position;

FIG. 10 is a plan view taken on line 1010 of FIG. 8-but including the release plate actuating cam;

FIG. 11 is a similar view to FIG. 10 illustrating the release plate actuated;

FIG. 12 is a perspective view of the'punch alignment plate;

FIG. 13 is a perspective view of the base unit removable paper carrier plate;

rangement, and

FIG. 15 is a representation of a test paper used in the device.

DESCRIPTION OF THE PREFERRED EMBODIMENT This device is intended primarily for use in grading preprinted true-false test papers by punching holes into the preslidably received within bushing elements 37, as shown in FIG.

1. Similar guide pins and bushings are provided both fore and printed sheets, the punched holes corresponding to the correct answers in a quiz which provides, for example, for four. possible answers to each of 50 questions; Such a test paper is illustrated in FIG. 15.

The device provides a key bank which, in the preferred embodiment, is divided into a total of fifty rows of four keys to a row. The 50 rows are arranged into three columns containing l7, l7 and 16 rows respectively to correspond with an arrangement of blanks on the test papers.

Referring now by characters of reference to the drawings, and first to FIGS. 1', 2 and 3, it will be understood that the punching device comprises a base unit 10 and a superjacent header unit 11 mounted in reciprocating relation to the base unit 10. Essentially, the device operates by depressing specific key plunger elements, mounted to the header unit 11 to lock related punch elements into a hard, punching condition. By turning a crank arm 30 forward and backward, the header unit 11 may be lowered and raised. This reciprocation action causes-said specific key punch elements corresponding to correct test answers to perforate a stack of test papers 19 which are carried by the base unit 10.

It will be observed-that the test paper 19 in FIG. includes a plurality of blanks generally indicated by numeral 100. The shaded blanks, indicated by numeral 101, correspond to perforations produced by the specific key punch elements.

Generally speaking, the punching device is symmetrical about its longitudinal center line except as noted in the following description. For this reason, like parts on each side of the device are given corresponding numerals. The base unit 10 includes opposed fore and aft side support members 12 and 13 attached as by screws 14 and 15to a bed plate 16. The header unit 11 is interconnected to the base unit 10 by fore and aft transverse shafts and 21 which extend through apertures 17 provided in the header unit 11. The shaft 20 is eccentrically journaled within the fore side support members 12 and the shaft 21 is eccentrically journaled within the aft side support members 13. Each of said support members 12 and 13 includes a substantially rectangular bearing aperture indicated by numerals 22 and 23 respectively which provide bearing surfaces 24 and 25 for offset earns 26 and 27 respectively provided at each end of the shafts'20 and 21. As shown in FIG. 14, the offset cams 26 and 27 include bearing race elements 28 and 29 to facilitate rotation of the cams 26 and 27,. and said bearing race elements 28 and 29 have a diameter substantially equal to the height of the apertures 22 and 23. The eccentricity of the cams 26 and 27 relative to the axes of rotation of the pinions 31 and 32 and the degree of rotation induced into said pinions determine the reciprocating stroke.

The fore shaft 20 includes a crank arm 30 attached at one end by which the shaft 20 may be rotated. -T he fore and aft shafts 20 and 21 are tied together for concerted action by means of a rack and pinion assembly. The rack and pinion assembly includes opposed pinions 31, mounted at each end of the fore shaft 20, and opposed pinions 32 mounted at each end of the aft shaft 21. Rack members 33, disposed at each side of the header unit 11, interconnect associated fore and aft pinions 31 and 32 and slotted keep elements 34 and 35, connected to the header unit 11, retain the racks 33 in correct alignment, the racks 33 being slidably received within said keep elements 34 and 35.

The header unit 11 is maintained in register with the base unit 10 by guide pins 36 secured to the bed plates 16 and aft of the device, and constitute guide means between the base unit 10 and the header unit 11 which maintain these units in register as header unit 11 reciprocates relative to the base unit 10 upon rotation of the handle 30.-

The header unit 11 carries a plurality of key punch units 42 which include extended portions depending from the header unit 11. Each key punch unit 42 iscapable of being locked into a hard position so that it will selectively punch holes in a stack of paper sheets, such as test papers 19, when said test papers 19 are carried on the base unit 10.

Specifically, as shown in detail in FIGS. 4 and 5 respectively, the header unit includes a substantially pan-shaped gear housing 44 having a bottom plate 45. A wear plate 46 is rigidly attached to the underside of the bottom plate 45 and a cover plate 47 is provided which extends between and is supported by the fore and aft ends of the housing 44.

Each of the key punch units 42 includes a plunger element 51 and a punching element 52. The plunger elements 51 are mounted to the gear housing 44 and the punching elements 52 are carried by the bottom plate 54 of a pan-shaped retention housing 53 which forms part of the header unit 11 and constitutes a retention means. The retention housing 53, shown in detail in FIG. 7, is mounted in depending relation to the gear housing 44 and attached thereto as by fasteners (not shown).

' A release plate 50, which operates to unlock the key punch units 42 as will be described, is mounted below the gear housing wear plate 46 between the retention housing bottom plate 54 and said gear housing wear plate 46. This release plate 50,

shown in detail in FIG. 6, is suspended from the underside of the gear housing 44 by means of four comer bolts 55 threadedly received within associated apertures 67 provided in the wear plate 46. By virtue of slotted holes 56 provided in the release plate 50 and receiving said bolts 55, the release plate 50 is capable of transverse movement relative to the wear plate 46.

The test papers 19 which are to be punched are placed on a carrier plate 60 which rests on the bed plate 16. The carrier plate 60, shown in detail in FIG. 13, includes a pull handle 61. As shown in FIG. 1, the carrier plate 60 is slidably received within tracks provided by a pair of opposing angle members 62, which flank the carrier plate 60 and are attached'to the bed plate 16, the angle members 62 being preferably ofpla stic to facilitate the sliding action. The bed plate l6'also includes a pair of elongate plastic inserts 87, and said inserts 87 further facilitate the sliding action of the carrier plate 60. As shown in FIG. 13, the carrier plate 60 includes a pair of opposed positioning strips 66 which hold the test papers 19 in a correct transverse alignment for punching. A transverse stop bar 65,

extending between the angle members 62, as shown in FIG. 2,

provides a stop means locating the paper carrier plate 60 in correct longitudinal alignment. As shown in FIG. 1, the bed plate 16 is recessed to accommodate a plastic tray 64, the purpose of which is to catch the punchings.

An alignment plate 63, shown in detail in FIG. 12, is disposed above the carrier plate 60 and is supported by the angle members 62. This plate 62 constitutes a punch alignment means and has the function of laterally supporting and stabilizing the punch elements 52 at the remote end thereof. Plate 63 is held in register with the bed plate 16 by guide pins 36 slidably received by associated apertures 85 in the alignment plate 63. It will be observed from FIG. 12 that the alignment plate 63 includes a pair of arms 86. These arms 86 overlie and stiffen the plastic angle track members 62, as shown in FIG. 2.

With the exception of the release plate 50, the principal in: dividual components of the header unit 11, namely the gear housing 44 and the'retentionhousing 53, are held in vertical register by means of pins 36 and associated bushings 37. The

I bushings 37 extend between the gear housing 44 and the re-- tention housing 53 through apertures 38 and 39 provided in each of these respective components, as shown in FIGS. 5 and 7. Relative transverse movement between gear housing 44 and the retention housing 53 is thereby precluded. The cover plate 47 and the wear plate 46 are secured to the gear housing 44, as by threaded fasteners (not shown), and are likewise precluded from relative transverse movement.

Similarly, individual components of the base unit are precluded from relative transverse movement. .For example, the pins 36, which are secured to the bed plate 16, extend through apertures 85 which are provided in the alignment plate 63 and shown in FIG. 12. The carrier plate 60, on the other hand, which is capable of independent movement relative to the base unit 10, is maintained in register during punching by three chamfered alignment pins 57. As shown in FIG. 7, these pins 57 are secured to the retention housing bottom plate 54 as by fasteners 58. The pins 37 are slidably received by associated apertures 84 provided in the carrier plate 60 and shown in FIG. 13.

Each of the components of the base unit.10 and the header unit 11 noted above includes a plurality of key punch apertures which are in vertical register duringthe punching process. In each component, vertically associated apertures are aligned to receive one of the component parts 51 or 52 of the key punch unit 42, in sliding relation.

As shown in FIGS. 4 and 5, the gear housing cover plate 47 includes a plurality of circular apertures 43 adapted to slidably receive the plunger elements 51. The gear housing bottom plate 45 and wear plate 46 are secured together and may be considered as a single element having a plurality of circular apertures 48 which extend through both the bottom plate 45 and the wear 'plate 46 and which are adapted to slidably receive plunger elements 51. The circular apertures 48 are in register with associated apertures 43 in the cover plate 47 and said apertures 48 are interconnected by means of a plurality of longitudinal slots 49. The cover plate 47 and the gear housing bottom plate and wear plate combination provide upper and lower support means for the plunger elements 51.

As shown in FIG. 6, the release plate 50 includes a plurality of elongate transverse slots 74 which are interconnected by as sociated grooves 75. The grooves 75 provide opposed intermittent shoulder means flanking associated plunger elements 51 and are adapted to engage and unlock said plunger elements 51 as will be later described. The transverse slots 74 are substantially in register with transverse groups of four each of the aforementioned apertures 43 and 48 of the gear housing 44. 1

As show in FIG. 7, the retention housing 53 includes a plurality of circular apertures 59 adapted to slidably receive the punch elements 52. The alignment plate 63 (FIG. 12) and the paper carrier plate 60 (F [G 13) likewise include a plurality of circular apertures, 68 and 69 respectively, which are also adapted to slidably receive the punch element 52, said associated apertures 59, 68 and 69 being vertically aligned.

FIGS. 8 through 11 illustrate in enlarged detail the structure of the key punch element 42 and the disposition of parts relative to the components of the header and base units 10 and 11 respectively. FIGS. 8 and 9 are similar in that one of the plunger elements 51 is indicated in a depressed condition. FIGS. 8 and 9 are different in that FIG. 8 indicates the header unit 11 in the raised position while FIG. 9 indicates the header unit 11 in the lowered, punching position.

Each plunger element 51 is connected to the gear housing 44 by a helical compression spring element 70. The upper end of each spring 70 is connected to its associated plunger element 51 by insertion of said upper end into a compatible hole 71. The lower end of the spring 70 is connected to the bottom plate 45 of the gear housing 44 by insertion of the lower end of the spring 70 into a hole 72 provided adjacent its associated plunger element 51.

Each plungerv element 51 includes a transverse latch pin 73. Each spring element 70 is overwound about the plunger element 51 to the extent of one-quarter turn so that when the plunger element 51 is in the inoperative non-depressed condition, it is under coil spring action and the latch pin 73 is thereby under spring-loaded pressure against the side walls of the slots 49. When the plunger element 51 is depressed, the spring element 70 is compressed and when the downward travel of the plunger element 51 is sufficient to cause the latch pin 73 to clear the undersurface of the wear plate 46, the latch pin 73 rotates under unwinding coil spring action. The effect of this rotation is to latch the plunger element 51 and prevent retraction of the plunger element 51 to its original position on release of digital pressure because the latch pin 73 engages the underside of the wear plate 46.

In order for retraction to occur, the latch pin 73 must be returned again to an unlatched, aligned position with the slot 49 in the wear plate 46. The rotation of the plunger element 51 to an unlatched position, is accomplished by the release plate 50, which is suspended below the wear plate 46 by bolts 55 (FIG. 6), and which is capable of transverse movement relative to the wear plate 46. FIG. 10 indicates the orientation of the depressed plunger element 51 in the latched position and it will be observed that the latch pin 73 of said depressed plunger element 51 tends to bear against opposing sides of the groove 75 provided in the release plate 50. When the release plate 50 is moved transversely to the left, the right-hand side of the groove 75 engages the latch pin 73 and urges said pin 73 counterclockwise to clear the sides of the slot 49. When the latch pin 73 clears the slot 79, retraction of said plunger element 51 occurs under the action of the compression spring element 70.

The release plate is moved transversely by means of an eccentric cam 80 disposed at the remote end of a release shaft 81. The shaft 81 extends through aperture 77, in the cover plate 47, and'the aperture 78, in the gear housing bottom and wear plates 45 and 46, and the cam 80 is accommodated within a slotted aperture 79 provided in the release plate 50. Rotation of the release shaft 81 clockwise about its own vertical axis by means of the shaft handle 82 causes the cam 80 to urge the release plate to the left, the axis of the release shaft 81 remaining relatively in the same position. This action is exemplified by a comparisonbetween FIGS. 10 and 11 which indicate, by means of a hypothetical marker line 83, the relative rotation of the release shaft 81. The relative movement of the cam from its initial to its release position is indicated by broken and full line representation respectively in FIG. 11. It will be understood from a comparison between FIG. 10 and FIG. 11 that neither the gear housing bottom plate 45 nor the wear plate 46 move. The same comparison with regard to the release plate 50, however, indicates that the release plate 50 has moved to the left, relative to said plates 45 and 46, under cam action. v

FIG. 6 clearly indicates the location of the release shaft 81 and it will be understood that the shaft 81 is precluded from vertical movement relative to the header unit 11 by a collar or other conventional means (not shown). The suspension bolts 55, which are threadedly engaged within the wear plate apertures 67, provide limit means operating within the slots 56. This arrangement permits the release plate 50 the necessary degree of transverse movement to accomplish the unlatching action, yet substantially precludes longitudinal movement.

When the header unit 11 is in the inoperative, raised position indicated in FIG. 8, the punch elements 52 are retained in depending relation in the retention housing 53 by the provision of a head 76 on each of said elements which engages the upper face of the retention plate 54. In the header raised position, a plunger element 51 in a depressed condition almost engages an associated head 76. There is, on the other hand, a substantial space between a punch element head 76 and a plunger element 51 which is not so depressed.

When the header unit 11 is lowered, the punch elements 52 ride upwardly on contacting the test papers 19. When this contact occurs, a depressed plunger element 51 engages its associated punch element 52 and effectively locks said punch element 52 in a hard position capable of perforating the test papers 19. A non-depressed plunger element 51 is sufficiently spaced from its associated punch element 52 so that engageform a part. When the rotation is sufficient for the latch pins r 73 to clear the sides of the wear plate slots 48, the plunger elethe gear housing bottom plate 45 and wear plate 46. FIG. 9 in:

dicates the disposition of parts when the header unit 11 is fully lowered. When the header unit 11 is returned to the inoperative, raised position, the punch elements 52 are simply lifted upwardly by the bottom plate 54 of the retention housing 53.

The plunger unlatching mechanism may be actuated immediately the header unit, 11 is raised or alternatively, the header unit 11 may be reciprocated as many times as desired witha selected group of key punch units 42 in the locked position. These selected plunger elements 51 will remain depressed until the release mechanism is actuated and thus, one punch setting may be maintained as-long as required.

It is thought that the structural'features and functional adpapers are correctly aligned within the device.

With the crank arm 30 turned so that the header unit 11 is in its raised position, selective key punch units 42, corresponding to correct test answers, are digitally depressed. The coil spring action of the spring element 70 locks these specific plunger elements 51 into a latched, hard position above associated punch elements 52, which depend below the underside of the header unit 11. The relative positions of the depressed and non-depressed plungers 51 is indicated clearly in FIG. 8. g

The punching action is effectuated by lowering the header unit 11. This-is accomplished by forward rotation of the handle '30. Such rotation turns both fore and aft rack-interconnec ted shafts 20 and 21, which extend between the base unit side support members 13 and 14 and the header unit 11.

.Reciprocating motion is induced into the header'unit 11 because of the offset cams 26 and 27, which are mounted at each end of the shafts'20 and 21 respectively and which bear on the side support members 13 and l4 and the header unit 11 is lowered in a vertical direction toward the base unit by virtueof the guide assembly provided by the pin and bushing elements 36 and 37 respectively.

Any discrepancy in the alignment of the carrier plate 60 is corrected by alignment pins 57 which depend from the underside of the header unit 11.

Associated punch elements 52 disposed below the depressed, latched plunger elements 51 are urged downwardly with the header unit 11 to punch the test papers 19. All other punch elements 52, on meeting the resistance of the test papers 19, are, relatively speaking, lifted upwardly into the recess provided by the registered apertures, below the nondepressed plunger elements 51, indicated by numeral 48 in the wear'plate 46.

When the punching action is completed, the header unit 11 is returned to its raised position by simply rotating the crank handle 30 rearwardly. This cycle of operations may be repeated as often as desired.

When it is desired to released the locked plunger elements 51 to prepare for a newkey setting, the release plate'50 is actuated into'transverse motion by turning the release handle 82. This action rotates a cam 80 disposed within a slotted hole A 79 in the release plate 50 as indicated in FIG. 6 and induces the required transverse motion into said release plate 50. The

bolts 55, disposed within the slots 56, insure that the motion of the release plate 50 will be transverse rather than longitudinal and-this transverse movement urges the sides of the release plate grooves 75 against the latch pins 73 rotating said latch pins 73 and associated plunger elements 51 of which they 1 vantages of this punching device have become fully apparent ments 51 are automatically retracted under the action of the compression spring element 70. The device is now ready for a new key setting correspondingto a different set of test papers.

it will be understood that as the crank arm is turned, the axes of the shafts 20 and 21 tend to orbit about the axes of rotation of associated ball races 28 and29 respectively (see FIG. 14). However, becauseof the guide means provided by pins 36 and bushings "37 relative fore and aft movement between the base unit 10 and header unit 11 is inhibited and only vertical movement occurs, the ball races 28 and 29 undergoing fore and aft movement. V

The relatively close vertical ,fit of the ball races 28 and 29 within the journal apertures 22 and 23 precludesany upward movement of the ball races 28 and 29 relativeto the base unit 10 when the punch elements 52in the hard, punching condition meet a considerable obstruction such as a thick stack of test papers 19. Thus, when the weight of the header 1 1 is alone insufi'icient to urge the punch elements 52 downwardly, the

' ball races 28 and29 bear against the upper portion of the apertures 22 and 23. This upward force is resisted by the weight of the base unit 10 and thus the weight of the 'device as a whole, and any support to which it may be attached, augments the paper punching action.

We claim as our invention: 1. A device for selectively punching paper sheets or the like, comprising:

a. base means, Y

b. header means mounted in reciprocating relation to the base means,

c. punching means carried by at least one of said means, the

punching means including:

1. a punch element mounted in movable relation to one of said means, and

2. a rotatable plunger element mounted in movable relation to one of said means and being selectively rotatable to a latched position for engagement with the punch element to lock-thepunch element in a punching position,- and l d. actuating means between the base means and the header means inducing reciprocating motion into one of said means.

2. -A punching device as defined inclaim 1, in which:

e. release means engageable with the plunger element selectively rotates the plunger element to unlock the punch element. g v

3. A device for selectively punching paper sheets or the like,

comprising:

a. base means, I

b. header means mounted in reciprocating relation to the base means,

c. punching means carried by the header means, the

punching means including:

l. a punch element mounted in movable relation to the header means, and v 2. locking means cooperating with the header means to selectively lock the punching element in a punching position, 1

d. actuating means between the base means and the header means inducing reciprocating motion into one of said means,

e. the locking means including a plunger element depressih. the latching means includes a projecting latch element provided on the plunger element,

i. the header means includes mounting means aligning the plunger element, the mounting means having an aperture receiving the plunger element in slidable relation and an abutment engaging the latch element in the latched position,

j. the release means includes a compatible latch shoulder engageable with the latch element to unlatch the plunger element.

5. A punching device as defined in claim 4, in which:

k. the release means includes a release plate having a transverse slot adapted to receive the plunger element and the release plate provides the shoulder means, and

1. release cam means carried by the header means moves the release plate relative to the mounting means whereby to rotate the plunger element to the unlatched position.

6. A device for selectively punching paper or the like, comprising:

a. base means,

b. header means mounted above the base means,

c. a plurality of longitudinal and transverse rows of punching units carried by at least one of said means, each punching unit including:

1. a depressible key plunger element mounted to one of said means in latchable relation,

2. a punch element mounted in movable relation to one of said means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punch elements being disposed in substantial axial alignment,

d. a plurality of key plunger elements in any longitudinal or transverse row being consecutively latchable without releasing any latched plunger element in the same row,

. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, l v

. guide means between the base means and the header means maintaining said header means and base means in alignment, and

g. release means selectively unlatching depressed plunger elements.

7. A device for selectively punching paper sheets or the like,

comprising:

a. base means,

b. header means mounted above the base means, 1

c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means,

d. guide means between the base means and the header means maintaining said header means and base means in alignment,

e. a plurality of punching units carried by the header means,

each punching unit including: 7 l. a depressible key plunger element mounted to the header means in latchable relation,

2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment,

f. release means selectively unlatching depressed plunger elements,

g. the actuating means including a pair of shafts mounted on the header means in side-by-side relation, each shaft including cam means,

h. coupling means interconnecting the shafts in rotative relation whereby rotation of one shaft rotates both cam means,

i. the base means including side support members, ad-

jacently disposed to each end of the shafts, each side member including journal means, and

j. the cam means including offset ball race elements secured to each end of each shaft in translational relation to an associated journal means.

8. A punching device as defined in claim 7, in which:

k. the coupling means includes pinion elements secured to each shaft, and a rack element mounted in movable relation to the header means and extending in operatively engaging relation between associated pinion elements.

9.'A device for selectively punching paper or the like, comprising:

a. base means,

b. header means mounted above the base means,

c. actuating means between the base means and the header means including cam means reciprocating the header means'relative to the base means,

d. guide means between the base means and the header means maintaining said header means and base means in alignment,

e. a plurality of punching units carried by the header means,

each punching unit including:

1. a depressible key plunger element mounted to the header means in latchable relation,

2. a punch element mounted in movable relation to the header ineans and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment,

f. releasemeans selectively unlatching depressed plunger elements,

g. the header means including a housing having upper and lower support means, disposed in spaced relation, each support means including a plurality of associated apertures, associated apertures of each support means being aligned to receive an associated key plunger element disposed in extended sliding relation between the upper and lower support means,

h. each plunger unit including spring means interconnecting the key plunger element to the header means, the spring means being adapted to rotate a depressed plunger element to a latched position and on unlatching, to return the plunger element to a non-depressed position,

i. the header means including a retention means disposed in spaced, subjacent relation to the housing and having a plurality of apertures aligned with associated apertures in the housing, each aperture receiving a punch element in sliding, retained relation, and V j. selectively latched plunger elements being adapted to engage and lock associated punch elements.

10. A punching device as defined in claim 9, in which:

k. the release means includes a release plate carried by the header means in transversely movable relation, the release plate including a plurality of slots receiving the plunger elements.

11. A punching device as defined in claim 10, in which:

1. the spring means includes a helical spring disposed about each plunger element in overwound relation whereby to torsionally spring-load said plunger element.

12. A punching device as defined in claim 10, in which:

I. each plunger element includes a projecting latch element,

in. the apertures of the lower support means engagingly retain the projecting elements in the non-depressed condition and said lower support means includes an abutment face engaging said latch elements in the depressed condition,

n. the spring means torsionally spring-loads said plunger elements whereby said latch elements are rotatable to a latched position engaging the abutment face in the depressed condition,

o. the release plate is disposed subjacently of the lower support means and includes shoulder means, adjacent each latch element in the latched condition, and engageable therewith, said release plate being adapted for translational movement relative to the lower support means whereby the shoulder means engages and rotates an associated latch element into alignment with an associated aperture in the lower support means.

13. A punching device as defined in claim 10, in which:

1. release cam means carried by the header means is disposed in operatively engaging relation with the release plate to induce translational movement into the release plate.

14. A punching devicejas defined in claim 10, in which:

l. the guide means between the base means and the header means includes a plurality of compatible pin and bushing elements, said pin elements being attached to one of said latter two means and the bushing elements being attached to the other of said latter two means.

15. A device for selectively punching paper or the like,

comprising:

a.basemeans, I; 6

b. header means mounted above the base means,

c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, 1

d. guide means between the base means and the header means maintaining said header means and base means in alignment,

e. a plurality of punching units carried by the header means,

' each punching unit including:

1. a depressible key plunger element mounted to the header means in latchable relation,

2. a punch element mounted in movable relation to the headermeans and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being 1 disposed in substantial axial alignment,

f. release means selectively unlatching depressed plunger elements .g. the base means including a removable carrier means adapted to carry the paper sheets, and

h. the paper carrier means including a plurality of apertures operatively aligned with associated punch elements, each of said apertures in .the paper carrier means being adapted to selectively receive a punch element whereby to punch the sheets. 16. A punching device as defined in claim 15, in which:

i. pin means attached to the header means and disposed between the header means and the paper carrier means, engages and aligns said carrier means .with said header means.

17. A device for selectivelypunching paper or the like,

comprising:

a. base means,

b. header means mounted above the base means,

c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means,

d. guide means between the base'means and the header means maintaining said header means and base means in alignment,

e. a plurality of punching units carried by the header means,

each punchingunit including:

1. a depressible key plunger element mounted to header means in latchable relation,

2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger the element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment,- f. release means selectively unlatching depressed plunger 5 I elements,

g. the header means including support means having a plurality of apertures receiving and supporting associated key plunger elements in sliding relation, h. eac punch element including a head, and

i. the header including aretention means disposed in spaced, subjacent relation to the support means and hav-' ing a plurality of apertures aligned with associated apertures in the housing, r j. each aperture receiving a punch element in freely depending relation, and each punch element head engaging the retention means'whereby punch elements aligned with unlatched plunger elements are movable relative to the retention means when the headermeans is lowered and punch elements aligned with latched plunger elements are lifted by the retention means when the header means israised.

18. A punching device as defined in claim 6, in which:

h. the punch elements are freely mounted insuspendable relation to the header means, and I stabilizing the punch elements. v

19. The method of grading test papers by punching the papers at preselected points corresponding to correct, multiple choice quiz answers, the method comprising the steps of:

- above a plurality of associated punch elements,

b. torsionally spring-loading the key plunger elements,

c. detaining said key plunger elements,

d. depressing selected key plunger elements corresponding to correct test answers out of detention to a rotatedlatch position to lock associated punch elements,

' e. aligning a stack of test papers below the punch elements,

f. reciprocating the key bank to punch the test papers, and

g. rotating said selected key plunger elements out of the latched position to torsionally spring-reload key plunger elements.

20. A method of grading test, papers as defined in claim 19,

comprising the additional steps of: a

h. axially spring-loading the selected key plunger elements as said key plunger elements are depressed into the latched position, and

i. returning the selected key plunger elements to the nondepressed condition after said key plunger elements are rotated out of the latched position.

reciprocating relation to the d. actuating means between the base means and the header means inducing reciprocating motion into one of said 5 means.

i. the'bas'e means includes alignment means engaging and I a. aligning a plurality of key plunger elements in a 'key bank said selected 21. A device for selectively punching paper sheets or the 

1. A device for selectively punching paper sheets or the like, comprising: a. base means, b. header means mounted in reciprocating relation to the base means, c. punching means carried by at least one of said means, the punching means including:
 1. a punch element mounted in movable relation to one of said means, and
 2. a rotatable plunger element mounted in movable relation to one of said means and being selectively rotatable to a latched position for engagement with the punch element to lock the punch element in a punching position, and d. actuating means between the base means and the header means inducing reciprocating motion into one of said means.
 2. a rotatable plunger element mounted in movable relation to one of said means and being selectively rotatable to a latched position for engagement with the punch element to lock the punch element in a punching position, and d. actuating means between the base means and the header means inducing reciprocating motion into one of said means.
 2. A punching device as defined in claim 1, in which: e. release means engageable with the plunger element selectively rotates the plunger element to unlock the punch element.
 2. locking means cooperating with the header means to selectively lock the punching element in a punching position, d. actuating means between the base means and the header means inducing reciprocating motion into one of said means, e. the locking means including a plunger element depressible to a latched position engageable with the punch element, f. latching means retaining the plunger element selectively and automatically in the depressed position, the latching means including:
 2. a punch element mounted in movable relation to one of said means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punch elements being disposed in substantial axial alignment, d. a plurality of key plunger elements in any longitudinal or transverse row being consecutively latchable without releasing any latched plunger element in the same row, e. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, f. guide means between the base means and the header means maintaining said header means and base means in alignment, and g. release means selectively unlatching depressed plunger elements.
 2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment, f. release means selectively unlatching depressed plunger elements, g. the actuating means including a pair of shafts mounted on the header means in side-by-side relation, each shaft including cam means, h. coupling means interconnecting the shafts in rotative relation whereby rotation of one shaft rotates both cam means, i. the base means including side support members, adjacently disposed to each end of the shafts, each side member including journal means, and j. the cam means including offset ball race elements secured to each end of each shaft in translational relation to an associated journal means.
 2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment, f. release means selectively unlatching depressed plunger elements, g. the header means including a housing having upper and lower support means, disposed in spaced relation, each support means including a plurality of associated apertures, associated apertures of each support means being aligned to receive an associated key plunger element disposed in extended sliding relation between the upper and lower support means, h. each plunger unit including spring means interconnecting the key plunger element to the header means, the spring means being adapted to rotate a depressed plunger element to a latched position and on unlatching, to return the plunger element to a non-depressed position, i. the header means including a retention means disposed in spaced, subjacent relation to the housing and having a plurality of apertures aligned with associated apertures in the housing, each aperture receiving a punch element in sliding, retained relation, and j. selectively latched plunger elements being adapted to engage and lock associated punch elements.
 2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, saId plunger and punching elements being disposed in substantial axial alignment, f. release means selectively unlatching depressed plunger elements, g. the header means including support means having a plurality of apertures receiving and supporting associated key plunger elements in sliding relation, h. each punch element including a head, and i. the header including a retention means disposed in spaced, subjacent relation to the support means and having a plurality of apertures aligned with associated apertures in the housing, j. each aperture receiving a punch element in freely depending relation, and each punch element head engaging the retention means whereby punch elements aligned with unlatched plunger elements are movable relative to the retention means when the header means is lowered and punch elements aligned with latched plunger elements are lifted by the retention means when the header means is raised.
 2. a punch element mounted in movable relation to the header means and engageable by the plunger element in the latched position whereby said latched plunger element locks the punch element in a punching condition, said plunger and punching elements being disposed in substantial axial alignment, f. release means selectively unlatching depressed plunger elements, g. the base means including a removable carrier means adapted to carry the paper sheets, and h. the paper carrier means including a plurality of apertures operatively aligned with associated punch elements, each of said apertures in the paper carrier means being adapted to selectively receive a punch element whereby to punch the sheets.
 2. a plunger element mounted in movable relation to the header means and latchable with the header means to selectively lock the punch element in a punching position, and d. actuating means between the base means and the header means inducing reciprocating motion into one of said means.
 3. A device for selectively punching paper sheets or the like, comprising: a. base means, b. header means mounted in reciprocating relation to the base means, c. punching means carried by the header means, the punching means including:
 4. A punching device as defined in claim 3, in which: h. the latching means includes a projecting latch element provided on the plunger element, i. the header means includes mounting means aligning the plunger element, the mounting means having an aperture receiving the plunger element in slidable relation and an abutment engaging the latch element in the latched position, j. the release means includes a compatible latch shoulder engageable with the latch element to unlatch the plunger element.
 5. A punching device as defined in claim 4, in which: k. the release means includes a release plate having a transverse slot adapted to receive the plunger element and the release plate provides the shoulder means, and l. release cam means carried by the header means moves the release plate relative to the mounting means whereby to rotate the plunger element to the unlatched position.
 6. A device for selectively punching paper or the like, comprising: a. base means, b. header means mounted above the base means, c. a plurality of longitudinal and transverse rows of punching units carried by at least one of said means, each punching unit including:
 7. A device for selectively punching paper sheets or the like, comprising: a. base means, b. header means mounted above the base means, c. actuating means between the base means and the header means includIng cam means reciprocating the header means relative to the base means, d. guide means between the base means and the header means maintaining said header means and base means in alignment, e. a plurality of punching units carried by the header means, each punching unit including:
 8. A punching device as defined in claim 7, in which: k. the coupling means includes pinion elements secured to each shaft, and a rack element mounted in movable relation to the header means and extending in operatively engaging relation between associated pinion elements.
 9. A device for selectively punching paper or the like, comprising: a. base means, b. header means mounted above the base means, c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, d. guide means between the base means and the header means maintaining said header means and base means in alignment, e. a plurality of punching units carried by the header means, each punching unit including:
 10. A punching device as defined in claim 9, in which: k. the release means includes a release plate carried by the header means in transversely movable relation, the release plate including a plurality of slots receiving the plunger elements.
 11. A punching device as defined in claim 10, in which: l. the spring means includes a helical spring disposed about each plunger element in overwound relAtion whereby to torsionally spring-load said plunger element.
 12. A punching device as defined in claim 10, in which: l. each plunger element includes a projecting latch element, m. the apertures of the lower support means engagingly retain the projecting elements in the non-depressed condition and said lower support means includes an abutment face engaging said latch elements in the depressed condition, n. the spring means torsionally spring-loads said plunger elements whereby said latch elements are rotatable to a latched position engaging the abutment face in the depressed condition, o. the release plate is disposed subjacently of the lower support means and includes shoulder means, adjacent each latch element in the latched condition, and engageable therewith, said release plate being adapted for translational movement relative to the lower support means whereby the shoulder means engages and rotates an associated latch element into alignment with an associated aperture in the lower support means.
 13. A punching device as defined in claim 10, in which:
 14. A punching device as defined in claim 10, in which:
 15. A device for selectively punching paper or the like, comprising: a. base means, b. header means mounted above the base means, c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, d. guide means between the base means and the header means maintaining said header means and base means in alignment, e. a plurality of punching units carried by the header means, each punching unit including:
 16. A punching device as defined in claim 15, in which: i. pin means attached to the header means and disposed between the header means and the paper carrier means, engages and aligns said carrier means with said header means.
 17. A device for selectively punching paper or the like, comprising: a. base means, b. header means mounted above the base means, c. actuating means between the base means and the header means including cam means reciprocating the header means relative to the base means, d. guide means between the base means and the header means maintaining said header means and base means in alignment, e. a plurality of punching units carried by the header means, each punching unit including:
 18. A punching device as defined in claim 6, in which: h. the punch elements are freely mounted in suspendable relation to the header means, and i. the base means includes alignment means engaging and stabilizing the punch elements.
 19. The method of grading test papers by punching the papers at preselected points corresponding to correct, multiple choice quiz answers, the method comprising the steps of: a. aligning a plurality of key plunger elements in a key bank above a plurality of associated punch elements, b. torsionally spring-loading the key plunger elements, c. detaining said key plunger elements, d. depressing selected key plunger elements corresponding to correct test answers out of detention to a rotated latch position to lock associated punch elements, e. aligning a stack of test papers below the punch elements, f. reciprocating the key bank to punch the test papers, and g. rotating said selected key plunger elements out of the latched position to torsionally spring-reload said selected key plunger elements.
 20. A method of grading test papers as defined in claim 19, comprising the additional steps of: h. axially spring-loading the selected key plunger elements as said key plunger elements are depressed into the latched position, and i. returning the selected key plunger elements to the non-depressed condition after said key plunger elements are rotated out of the latched position.
 21. A device for selectively punching paper sheets or the like, comprising: a. base means, b. header means mounted in reciprocating relation to the base means, c. punching means carried by the header means, the punching means including: 